Periodic gas generator

ABSTRACT

This periodic gas generator adapted for use notably as a volumetric respirator is designed for supplying gas during a fraction 1/n of the periodic time of operation of the generator, notably one-third of this time corresponding to the inspiration time period, the other two thirds enabling the user to expire the previously breathed gas, this invention permitting this cycle to take place irrespective of the generator frequency and also of the volume of gas delivered thereby.

United States Patent Beaumont [54] reiuomc GAS GENERATOR [72] Inventor: Georges Beaumont, 44 rue de Miromesnil, Paris 8e, France [22] Filed: May 24, 1971 [21] Appl. No.: 146,405

Related US. Application Data [63] Continuation-impart of Ser. No. 858,085, Sept.

15, 1969, abandoned.

[52] US. Cl ..137/8l.5 [51] Int. Cl. ..Fl5c 1/12 [58] Field of Search ..l37/8l.5; 128/1456, 145.7

[56] References Cited UNITED STATES PATENTS 3,124,160 3/1964 Zilberfarb ..137/81.5 3,128,039 4/1964 Norwood ..137/81.5 X 3,217,727 11/1965 Spyropoulos ..l37/8l.5 3,339,570 9/1967 Hatch ..l37/81.5

[4 1 Aug. 15, 1972 9/1967 Phillips ..l37/81 5 3,368,555 2/1968 Beasley ..l37/8l.5 X 3,379,194 4/1968 Ziermann ..l37/81.5 X

' 3,429,248 2/1969 Furlong ..137/8l.5 X 3,507,212 4/1970 Matteson ..l37/81.5 X 3,522,816 8/1970 Springer ..137/81.5 3,598,116 8/1971 Peters ..l37/81.5 X

Primary Examiner-Samuel Scott Attorney-Robert E. Burns and Emmanuel]. Lobato [5 7] ABSTRACT Thisperiodic gas generator adapted for use notably as a volumetric respirator is designed for supplying gas during a fraction 1/n of the periodic time of operation of the generator, notably one-third of this time corresponding to the inspiration time period, the other two thirds enabling the user to expire the previously breathed gas, this invention permitting this cycle to take place irrespective of the generator frequency and also of the volume of gas delivered thereby.

7 Claims, 9 Drawing figures Patented Aug. 15, 1972 3,683,951

3 SheetsSheet l Patented Aug. 15, 1972 3 Sheets-Sheet 2 3 Sheets-Sheet 5 Patented Aug. 15, 1972 W Q FL? m m I a 3 a y m S l H Q R R W mm\ H :v I; C E a a 3 G mm m mm x N mm 3 G 8 mm m wt PERIODIC GAS GENERATOR CROSS REFERENCES TO RELATED APPLICATION This application is a Continuation-in-Part of application Ser. No. 858,085, entitled: PERIODIC GAS GENERATOR, filed on Sept. 15th, 1969, now abancloned.

BACKGROUND OF THE INVENTION The present invention relates to periodic gas genera tors intended for use notably as a volumetric respirator.

Various types of apparatus are already known, for use either as artificial respiration apparatus or as relaxation apparatus, these apparatus being currently referred to the former as a respirator and the latter as a relaxer. Relaxers for example as described and illustrated in the US. Pats. Nos. 3,217,727, 3,472,225 and 3,494,357 are adapted to deliver a certain amount of gas on the users demand, during the breathing in cycle. These relaxers frequently incorporate a pneumatic oscillator and are thus controlled by the user himself; therefore, they cannot be used for reanimation purposes since they do not reproduce periodically the respiratory cycle.

Known respirators, such as the one described and illustrated in the U.S. Pat. No. 3,446,207, which reproduce artificially this respiratory cycle, consist of fluidic logic devices incorporating mechanical elements. However, these respirators are objectionable on account of many inconveniences, notably, inter alia,

the difficulty of preserving the fluid-tightness of the gas circuit means incorporating mechanical elements, and also the necessity for the user to inhale also the gas controlling these elements.

SUMMARY OF THE INVENTION It is a first object of the periodic gas generator according to the present invention to deliver a gas during one fraction 1/n of the time corresponding to its period of operation. More particularly, when considering the specific case of the application of the generator to a volumetric respirator, this fractionmay be one-third, i.e. corresponding to the breathing-in period, and dur' ing the two other thirds the user can expire the previously breathed gas.

It is another object of this invention to permit this cycle irrespective of the generator frequency and also of the volumetric amount of gas delivered by the apparatus.

It is a third object of the periodic gas generator according to this invention to supply these various pneumatic elements with control air that is not mixed with the air delivered by the apparatus to the user. This feature is particularly advantageous in case the generator is operated as a volumetric respirator.

A fourth object of the present invention consists in providing a generator wherein the circuits for the control gas and the output or users gas are perfectly tight, by using only static pneumatic component elements.

Furthermore, the present invention provides means whereby the aforesaid I/n fraction of the periodic gas generator can be modified at will by adding or removing a single type of pneumatic elements to or from the assembly, namely bistable amplifiers. Thus, generators delivering a gas during one time fraction corresponding to one/half, one/third, one/fourth etc.. of its period, may be contemplated, according, to the specific use for which it is intended.

The novel generator according; to this invention com? prises the combination of two separate sections supplied with high pressure and low pressure, and both connected to a common power relay. This power relay connected to the high-pressure source and to an output conduit delivering the gas is controlled during one fraction of the time period by a pneumatic clock or timer comprising a pneumatic oscillator, a monostable pneumatic amplifier and a plurality of bistable pneumatic amplifiers. These monostable and bistable amplifiers are known in the art as fluidic logic devices and their mode of operation is usually referred to as wall attachment or coanda effect.

These amplifiers incorporated in the periodic gas generator according tothe present invention are insensitive to vibration, shocks, ionizing radiations, electromagnetic fields, high temperatures and moisture. Thus, the generator according to this invention can operate without any maintenance and in any position and at all latitudes. In the case of a respirator, the apparatus according to this invention may be used on board ambulances for emergency operations and interventions, on emergency or rescue boats, on aircrafts or in submarine caissons. It is light in weight, of reduced dimensions and very simple to operate.

BRIEF DESCRIPTION OF THE DRAWINGS A clearer understanding of this invention may be had from the following description concerning an exemplary form of embodiment thereof given by way of illustration and illustrated in the attached diagrammatic drawings, in which: 1

FIG. I is a sectional view showing a known type of wall attachment effect bistable amplifier operating in a predeterminedposition;

FIG. 2 shows the same bistable amplifier in case of a change of position;

FIG. 3 illustrates the alternating oscillator;

FIG. 4 illustrates the monostable amplifier;

FIG. 5 is a sectional view of the pneumatic power relay;

FIG. 6 is a diagram illustrating the mounting of the various component elements of a generator adapted to deliver gas during one/third of its operating time;

FIG. 7 is a diagram showing the relationship between the opening and closing positions of the five pneumatic elements of FIG. 6, namely the oscillator, the monostable amplifier and first, second and third bistable amplifiers;

FIG. 8 is a front view of the generator according to this invention;

FIG. 9 isa side elevational view of the generator of F IG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 6, the amplifier comprises a gas source 1, to be referred to hereinafter as the highpressure source, which it connected via a conduit 2 to a power relay 3 to be described in detail presently. As it emerges from the output end 4 of power relay 3 the gas flows through a micrometric valve 5 controlled by means of button 6 permitting of adjusting the highpressure gas output delivered by the outlet conduit 7 during a fraction equal to l/n of the time corresponding to the period of operation of the generator. If this generator is operated as a volumetric respirator, the outlet conduit 7 is connected as conventional to known elements such as an economizer 8 connected in turn to a valve to which the respiratory mask may be fitted. An auxiliary device for reading the output pressure of the gas delivered by the conduit 7 may consist for example of a valve 9 and a pressure gage 10. The valve input is connected to the aforesaid economizer 8 and a control button 11 is provided so that by simply depressing it it is possible to read intermittently the value of the delivered gas pressure on the gage dial.

The conduits 2 and 7 interconnected via the power relay 3 and micrometric valve 5 constitute the highpressure circuit of the gas delivered by the apparatus. The intermittent operation of this circuit, so that a gas be delivered during one fraction l/n of the total time corresponding to its operating period, is monitored by a low-pressure source controlling the power relay 3 with its control inlet 12.

The necessary low-pressure source may consist of a secondary source, but a preferred solution aiming essentially at reducing the over-all dimensions of the apparatus consists in deriving one fraction of the highpressure gas from source 1 and to expand it to the desired lower pressure. Thus, it is clear that throughout the specification and claims herein the term highpressure is only relative to the low pressure of the gas used for monitoring the power relay 3. In actual practice, the high-pressure gas from source 1 is delivered at a relative pressure of about 40 to 45 psi, and the low pressure will depend of course on the fraction 1 /n to be obtained which may range from, say 4 to 7.5 psi.

The conduit 13 supplying high-pressure gas from source 1 comprises branch sections l4, l5 and 16. Each branch section has inserted therein a throttling device such as 17 adapted to deliver at its outlet a gas at the desired low pressure. The three branch sections are thus adapted to monitor the three different types of pneumatic component elements of the generator timer for delivering gas through the outlet conduit 7 during a fraction l/n of the time corresponding to the period of operation or cycle of the apparatus;

The various component elements of this pneumatic timer, for a given fraction l/n, are a pneumatic oscillator 18, a monostable amplifier 19 and n bistable pneumatic amplifiers, i.e., in the case illustrated in FIG. 6, for n is, three bistable amplifiers 20, 21, and 22.

The alternating oscillators 18 comprises an inlet 23 supplied with low pressure gas via branch line 16, and two outlets 24,.25 disposed symetrically in relation to said inlet. When the oscillator 18 is supplied, via the inlet 23, the gas output is by change through outlet 24 or outlet 25. If the gas emerges from outlet 24, a vacuum is produced at 25, and vice-versa. The outlet 25 is connected via a conduit 26 to a delay-action device 27 comprising a chamber 28 of which the useful volume is adjustable by means of a button 29. When the gas emerges from the oscillator via outlet 24, the time necessary for producing a vacuum at the other outlet 25 depends on the useful volume of chamber 28.

When this vacuum is obtained the gas jet is switched from 24 to 25, thus filling the chamber 28. When a sufficient pressure prevails in this chamber 28, the jet is switched again from outlet 25 to outlet 24 of oscillator 18. It is thus possible, by modifying the volume of chamber 28 to adjust the oscillator frequency while obtaining, as will be explained presently, a gas delivered during a fraction l/n of the time'corresponding to the period of operation of the generator. The outlet 24 of oscillator 18 is supplied with low-pressure gas n times per generator period.

The monostable amplifier 19 comprises an inlet 30 supplied with low pressure gas via branch line 15, and a pair of outlets 31 and 32 disposed on the other side of said inlet 30. Furthermore, it comprises two opposite control inlets 33 and 34. The gas is normally delivered through outlet 31 and a predetermined signal, for instance an overpressure at 33, will cause the gas to be delivered through the other outlet 32. Under these conditions it is only necessary to discontinue the signal applied to 33 or balance this signal by a similar one applied to 34 for automatically causing the gas jet to revert from outlet 32 to outlet 31. A first control inlet 33 is connected via conduit 35 to the outlet 24 of pneumatic oscillator 18. This conduit 35 comprises a branch line 36 having inserted therein a delay-action device 37. The branch line 36 is connected to the second control inlet 34. The function of delay-action device 37 is to extend the response time, i.e. to cause the gas flowing through conduit 35 to be directed towards the first control inlet 33 before attaining the second control inlet 34. The outlet 31 of monostable amplifier is vented to the atmosphere and the low pressure gas supplied to its inlet 30 is diverted from outlet 31 to outlet 32 as a consequence of this overpressure.

The n bistable amplifiers or like fluidic logic devices, in this case amplifiers 20, 21 and 22 operating according to the so-called coanda effect, are all identical and provided with an inlet such as 38 supplied separately with low pressure gas via sub-branch lines such as 39 and branch line 14. The first amplifier 20 comprises two outlets 40 and 41 disposed symetrically on either side of said inlet 38, and two control inlets 42 and 43. The gas penetrating through inlet 38 emerges at random 40 or 41, and a pneumatic control signal is necessary, whether at 43 or at 42, for diverting the low-pressure gas jet either towards 41 or towards 40. The second bistable amplifier 21 is also provided with two outlets 44 and 45 and two control inlets 46 and 47. When no signal is transmitted from a control inlet 42 or 43, the lower pressure gas supplied to inlet 38 is constantly deflected towards the outlet towards which it is being diverted. Similarly, the third amplifier 22 comprises two outlets 48 and 49 and two control inlets 50 and 51.

The second outlet 32 of monostable amplifier 19 is connected via conduits of gradually decreasing lengths to a first control inlet 43, 47 and 51 of bistable amplifiers 20, 21, and 22, respectively. The gas jet issuing from outlet 32 of monostable amplifier 19 is logically distributed among the bistable amplifiers 20 to 22. The high-pressure gas flows slowly in conduit 52 and the longer the path to a first control inlet of said bistable amplifier, the greater the delay brought in supplying the pneumatic control signal. Therefore, this signal will be delivered preferentially to bistable amplifier 20, then to amplifier 21 and eventually to amplifier 22.

These three bistable amplifiers 2h, 21 and 22 are so interconnected that opening the last amplifier 22 will close the two preceding ones. Thus, the first outlet 41 of bistable amplifier 21) is vented to the atmosphere, and the first outlet 49 of bistable amplifier 22 is connected to the second control inlet 42 of bistable amplifier 20. The second outlets 40 and 44 of the first and second bistable amplifiers and 21 are connected to the second control inlets 46 and 50 respectively of the next adjacent bistable amplifiers 21 and 22.

The second outlet 48 of the last bistable amplifier 22 is vented to the atmosphere.

The penultimate bistable amplifier 21 has its first outlet 45 connected to the control inlet 12 of power relay 3.

From the diagram of FIG. 6 illustrating more particularly a respirator delivering gas during one-third of the periodic time, i.e., during the breathing-in cycle, and delivering nothing during the remaining two-thirds of said period, which-is the expiration time, it will be seen that this structure may easily constitute a basis for any desired extrapolation, in order to deliver gas during a fraction l/n of it periodic time. In this case, the various connections between the n bistable pneumatic amplifiers connected through conduits of gradually increasing lengths from the first one to the n one to the second outlet of the monostable amplifier, may be obtained as follows:

The first outlet of each one of the (n2) first bistable amplifiers is vented to the atmosphere; the first outlet of the (nl),,, bistable amplifier is connected to the power relay, and finally the first outlet of the n bistable amplifier is connected to the second control inlet of the first bistable amplifier. The second outlet of each one of the first (rt-1), bistable amplifiers is connected to the second control inlet of the next adjacent amplifier, and the second outlet of the n or last amplifier is vented to the atmosphere. I

The power relay 3 illustrated in FIG. 5 comprises a case 53 enclosing a diaphragm 54 disposed beneath the relay control orifice 12 connected to the first outlet 45 of bistable amplifier 21. A round-headed piston 55 is resiliently urged upwards by a compression spring 56 and disposed under the diaphragm 54. The piston shank is provided with annular seals or packings 57 adapted, by engaging corresponding opposite seats formed in the case 53, to prevent the passage of air from conduit 2 to conduit 4 when the piston 55 is held in its normal upper position by the spring 56. When the low-pressure gas is delivered above the diaphragm 54 through orifice 12 the piston 55 is forced downwards so that the aforesaid conduits 2 and 4 are interconnected through the passage of case 53. Vent holes 58 are provided for draining any low-pressure gas having passed from conduit 2 to the underside of diaphragm 54 during the downwards movement of the piston.

A clearer understanding of the mode of operation of the volumetric respirator of FIG. 6 may be had by referring to FIG. 7 showing the relative positions of the gas jet towards one or the other of the outlets of each element as a function of time. It is thus apparent that the low-pressure gas can emerge from oscillator 18 via outlet 24 or 25, from monostable amplifier 19 via outlet 31 or 32 etc...

When'starting the generator, during the first filling 59 of chamber 28 through the first outlet 25 of oscillator 18, the low pressure air emergTng from monostable amplifier 19 flows via outlet 31 to the atmosphere. The three bistable amplifiers are so interconnected that the exit of air through outlets 40, 44 and 48 is maintained by the same air as that acting through the control inlets 46 and 50. When chamber 28 is drained for the first time at 60, with a slight time-lag due to the signal transmission through conduit 35, the air jet into the monostable amplifier 19 is diverted from outlet 31 to outlet 32 as illustrated at 61 in the diagram. This air jet issuing from 32 is delivered with a slight time-lag to the first control inlet 43 of the first bistable amplifier 211, thus causing the switching at 62 of the air jet in this bistable amplifier from its outlet 44) to the other outlet 41 connected to the atmosphere. The air jet from outlet 32 did not have sufficient timeto flow through conduit 52 to the control inlet 47 of bistable amplifier 21 for the air flowing through branch line 36 reached before that time the second control inlet 34 of the monostable amplifier for cancelling, as shown diagrammatically at 63, the signal by causing the air jet tobe switched back from 32 to 31 in monostable amplifier 19.

During. a second filling 64 of chamber 28, only the air jet from bistable amplifier 20 has been switched from the first outlet 41 to. the second outlet 40. During the second discharge 65 the second outlet 32 of the monostable amplifier is again supplied as shown at 66, thus causing the outlet 45 of bistable amplifier 21 to be supplied with gas with a slight time-lag, as shown diagrammatically at 67. Then the low-pressure gas is delivered to the control inlet 12 of power relay 3, thus enabling the, high-pressure gas from conduit 2 to flow through conduit 4 to the outlet conduit 7.

Another filling 68 and another draining 69 of chamber 28 causes as in the case of bistable amplifiers 2d and 22 the gas jet to be switched from outlet 48 to outlet 49 of amplifier 22, as shown diagrammatically at 71) (F IG. 7). The low-pressure air emerging from outlet 49 acts firstly upon the second control inlet 42 of bistable amplifier 20, thus causing the switching (shown at 71) of the gas jet from outlet 41 to outlet 4%. Thus, outlet is supplied with gas and acts with a slight delay on the second control inlet 46 of bistable amplifier 21 as shown at 72, so that the gas jet is switched from outlet to outlet 44. Subsequently, the control inlet 12 of power relay 3 is no more supplied with gas, and the passage of high-pressure gas from conduit 2 to conduit 4 is cut off.'The gas jet issuing from outlet 44 is then directed to the second control inlet of bistable amplifier 22 in order to produce the switching shown at 73 of the gas jet from outlet 49 to outlet 43, therefore, to the venting and draining step. Thus, a time period P of the generator has been accomplished, during which the gas was delivered only during a time period P through outlet conduit 7. During this time, the outlet 24 of oscillator 18 was supplied periodically n times, as shown at 60, 64 and 69. During each supply of gas to the outlet 24 of oscillator 18, a single bistable amplifier was controlled through the intermediary of the monostable amplifier. Since the bistable amplifier connected to the power relay 3 is set in its (n-l) position, it will be supplied with gas during a time period corresponding to l/n of the period P of operation of the generator, for the n amplifier, when open, will cause immediately, except for the unavoidable time-lag, the closing of (n-l) amplifiers preceding it. It will be noted that to simplify the diagram of FIG. 7 these delay time period of the various signals from one element to another of the pneumatic clock have been increased far beyond the normal proportions.

FIG. 8 and 9 illustrate on the other hand the extreme case with which the above-described generator can be transported. This generator may be contained entirely in a relatively small cabinet 74 having disposed on one main panel the control buttons 6 and 29 and the windows 75 and 76 for adjusting the volume and fre-quency, respectively, and also the control knob 11 for reading the pressure gage 10. On one side panel of this cabinet are the plug device for connecting the apparatus to the source 1 and the other plug means 77 and 79 for connecting the apparatus to the economizer 8.

It will readily occur to those conversant with the art that the specific and typical form of embodiment shown and described herein should not be construed as limiting the present invention since various modifications and relative arrangements of parts may be brought and contemplated therein without departing from the basic principle of the invention as set forth in the attached claims.

What I claim is:

l. A periodic gas generator adapted to deliver a gas during a fraction 1/n of the time corresponding to its period of operation for use notably as a volumetric respirator, which comprises a source of high-pressure gas, a power relay connected to said high-pressure source, an outlet conduit connected to said relay delivering high-pressure gas during a time 1/n, a source of low-pressure gas, a pneumatic oscillator monitored by said low-pressure source and having its outlet supplied with gas n times per period, a monostable pneumatic amplifier monitored by the low-pressure source, which comprises two outlets, of which the first outlet or inoperativeoutlet is connected to the atmosphere, and two control inlets connected to the oscillator outlet, a delay action device connected between a control inlet of said amplifier and the oscillator output, n bistable pneumatic amplifiers monitored by said low-pressure source and having each first and second control inlets and first and second outlets, conduit means connecting the second outlet of said monostable amplifier to the first control inlets of said 11 bistable amplifiers,

said conduit means having lengths decreasing from the first to the nth bistable amplifier, the first outlet of each one of the (n-2) bistable amplifiers being connected to the atmosphere, the first outlet of the (12-1 th bistable amplifiers being connected to the power relay, the first outlet of the nth bistable amplifier being connected to the second control inlet of the first bistable amplifier, the second outlet of each one of the (n-l) first bistable amplifiers being connected to the second control inlet of the following bistable amplifier, the second outlet of the nth bistable amplifier being connected to the atmosphere.

2. Periodic gas generator as set forth in claim 1, which comprises conduit means having fixed throttling means inserted along their paths, said conduit means being connected on the one hand to the high-pressure source and (K1 the other to the B n euma 'c oscillator, to the monosta e pneumatic amp er an to said n bistable amplifiers.

3. Periodic gas generator as set forth in claim 1, comprising means disposed between said high-pressure gas outlet of said power relay and the outlet conduit delivering the high-pressure gas, adapted to adjust the volume of gas delivered thereby.

4. Periodic gas generator as set forth in claim 1, comprising means responsive to said high-pressure gas delivered through said outlet conduit and adapted to measure and display the pressure of the gas delivered by the generator.

5. Periodic gas generator as set forth in claim 1, adapted to be operated as a volumetric respirator, which comprises three bistable amplifiers of the fiuidic logic type, and economizer supplied with high-pressure gas via said outlet conduit, and a respiratory mask connected to said economizer.

6. Periodic gas generator as set forth in claim 1, comprising a pneumatic oscillator comprising an inlet supplied with gas from said low-pressure source, and two outlets disposed symmetrically in relation to said inlet, the first outlet being connected to a constant-volume chamber, and the second outlet supplied n times per period being connected to the two control inlets of said monostable pneumatic amplifier.

7. Periodic gas generator as set forth in claim 6, which comprises means for modifying the constant volume of said chamber before the generator operation. I g 

1. A periodic gas generator adapted to deliver a gas during a fraction 1/n of the time corresponding to its period of operation for use notably as a volumetric respirator, which comprises a source of high-pressure gas, a power relay connected to said high-pressure source, an outlet conduit connected to said relay delivering high-pressure gas during a time 1/n, a source of lowpressure gas, a pneumatic oscillator monitored by said lowpressure source and having its outlet supplied with gas n times per period, a monostable pneumatic amplifier monitored by the low-pressure source, which comprises two outlets, of which the first outlet or ''''inoperative'''' outlet is connected to the atmosphere, and two control inlets connected to the oscillator outlet, a delay action device connected between a control inlet of said amplifier and the oscillator output, n bistable pneumatic amplifiers monitored by said low-pressure source and having each first and second control inlets and first and second outlets, conduit means connecting the second outlEt of said monostable amplifier to the first control inlets of said n bistable amplifiers, said conduit means having lengths decreasing from the first to the nth bistable amplifier, the first outlet of each one of the (n-2) bistable amplifiers being connected to the atmosphere, the first outlet of the (n-1) th bistable amplifiers being connected to the power relay, the first outlet of the nth bistable amplifier being connected to the second control inlet of the first bistable amplifier, the second outlet of each one of the (n-1) first bistable amplifiers being connected to the second control inlet of the following bistable amplifier, the second outlet of the nth bistable amplifier being connected to the atmosphere.
 2. Periodic gas generator as set forth in claim 1, which comprises conduit means having fixed throttling means inserted along their paths, said conduit means being connected on the one hand to the high-pressure source and on the other to the pneumatic oscillator, to the monostable pneumatic amplifier and to said n bistable amplifiers.
 3. Periodic gas generator as set forth in claim 1, comprising means disposed between said high-pressure gas outlet of said power relay and the outlet conduit delivering the high-pressure gas, adapted to adjust the volume of gas delivered thereby.
 4. Periodic gas generator as set forth in claim 1, comprising means responsive to said high-pressure gas delivered through said outlet conduit and adapted to measure and display the pressure of the gas delivered by the generator.
 5. Periodic gas generator as set forth in claim 1, adapted to be operated as a volumetric respirator, which comprises three bistable amplifiers of the fluidic logic type, and economizer supplied with high-pressure gas via said outlet conduit, and a respiratory mask connected to said economizer.
 6. Periodic gas generator as set forth in claim 1, comprising a pneumatic oscillator comprising an inlet supplied with gas from said low-pressure source, and two outlets disposed symmetrically in relation to said inlet, the first outlet being connected to a constant-volume chamber, and the second outlet supplied n times per period being connected to the two control inlets of said monostable pneumatic amplifier.
 7. Periodic gas generator as set forth in claim 6, which comprises means for modifying the constant volume of said chamber before the generator operation. 